Stone, brick, concrete and ceramic patio tiles sometimes have a common problem during the hot humid months of summer: They sweat. The condition may occur because of the tiles' porous structure; when tiles are not installed properly, increased water levels from summer rains can seep upward to the tiles' surface. Another reason for the sweating is the tiles' position on cool ground; when the cool patio surface meets warm, humid air, condensation develops on the tiles. A few options can correct the causes of tiles sweating.
Cut back landscaping plants around the patio area. Doing so opens the area, allowing air to flow more freely than it could previously. Trim back branches with pruning sheers and a hand-saw, making each cut at a 45-degree angle just in front of a leaf. Do not cut back more than one-third of a branch.
Remove some of the shrubs or other plants surrounding the patio if the area is too crowded and blocks sunlight and/or air flow. Allowing a breeze to move over the patio surface helps dry the tiles' sweat more quickly, and opening the area allows more sunlight, which helps warm the tile surface and prevents some, if not all, condensation.
Remove all objects, such as furniture, from the patio. Pour a stone, brick, masonry or ceramic tile cleaner on the tiles, using only the cleaner for your kind of tiles and following the cleaner container's directions for application. Use a long-handled bristle brush or broom to remove dirt buildup and other grime from the tiles. Rinse off the tiles with water.
Pour a stone, brick, masonry or ceramic tile sealant in a paint tray, using only the sealant meant for your type of tiles. Dip a roller applicator in the sealant, and use the roller to apply the sealant to the tiles, covering the tiles evenly with the sealant. Run the roller over the tile surface in even strokes to cover the tiles. Allow the sealer to dry for one full day before placing furniture back on the patio. Sealant prevents water from seeping through the ground and reaching the tile surface.